Do try this at home

Enzymes in action

Why does this work?

Enzymes are involved in a huge number of processes in the human body - every job has an enzyme to do it. You can easily see enzymes at work using fresh pineapple and gelatin.

Ingredients

• Fresh pineapple
• Jelly (if you are American, you will need Jello, not the stuff that you stick on toast and call jelly)
  

Recipe

Make some jelly/jello according to packet instructions and allow to set in two glass bowls. (Get someone to help you with the boiling water if you're likely to burn yourself).

Cut up the pineapple into rings (Don't cut any fingers off with the knife) and add a ring to one of the jellys.

Leave the jelly for a bit and check back every now and then to see what happens. Compare the two jellys - the one with no pineapple is known as the negative control.

When you've finished, eat the second jelly that hasn't been ruined by putting pineapple in it.

The clever thing about enzymes is that they don't get used up in a reaction - they come out at the end exactly the same as they went in. This means that the pineapple will still be pineapple at the end of this experiment and you can fish it out of the jelly and eat it too.

When I was younger I was convinced that pineapple and kiwis removed the top surface of my tongue as I was left in considerable pain when I ate large amounts of these fruits. At the time, my parents just laughed and said "Yes dear, of course dear", but I now know that I was, in fact, right. This is because these fruits contain large amounts of protease enzymes that act to break down long polypeptides into their constituent amino acids. In other words, the fruit was breaking down the proteins making up my tongue. Nice.

It would be interesting to find out how much pineapple is required to break down an entire human tongue, but so far I've found no one willing to part with their tongue. Oh well, today's experiment makes do with Jelly - this contains proteins called gelatins. The pineapple enzyme is called bromelain and it breaks down gelatins. This is why jelly manufacturers warn you against putting pineapple and kiwi into jellys on the packets! I think fruit ruins the flavor of jelly any way.

For the more blood thirsty among you, you can show another enzyme at work using some calf's liver and hydrogen peroxide. Drop a little bit of liver into 20% hydrogen peroxide and you will be able to see the oxygen bubbles released as the catalase enzyme in the liver breaks down the hydrogen peroxide (try and find out why catalase is a really important enzyme in the body for extra points).You can even try boiling the liver first too and looking at what effect this has. Hydrogen peroxide is really dangerous though, so if you're interested in testing out this experiment, ask your parents or teacher to get everything ready for you and then you won't risk burning your hands off with the hydrogen peroxide.

Related pages: About Enzymes - Amylase - Extract DNA

This work is licenced under a Creative Commons Licence.